Window roller blinds in motor vehicles are used for the purpose of reducing interior heating in order to minimize air-conditioning system requirements. In terms of direct sun irradiation, in the summer when the sun rises high in the sky, the rear window is especially vulnerable because it lies relatively flat. Depending on the driving direction, sunlight nearly always comes through the rear window and the exposed parts of the vehicle beneath the rear window are heated significantly. Therefore, rear-window roller blinds have become relatively widely used in vehicles.
In a known rear-window roller blind shown in DE 102 48 591 A1, a rotatably supported wind-up shaft is located underneath a rear shelf below the window. A roller blind is fixed to the wind-up shaft with one edge, and the roller blind can be pulled out through a slot in the rear shelf. The slot divides the rear shelf into two parts, namely one part that is adjacent to the rear seat back and one part that borders the rear window. In the inner lining of the C-column of the vehicle body for a four-door vehicle, there are two mirror-inverted guide rails, which extend into the space under the rear shelf directly in the region of the slot in the rear shelf. The top edge of the guide rails lies flush underneath the top roof edge of the rear window. The two mirror-inverted guide rails are used for guiding movement of a pull rod assembly to which the roller blind is fixed at its opposite edge.
The pull rod assembly is straight and adjustable in its longitudinal length. It can be moved from a rest position, in which the slot in the rear shelf is essentially closed, into a functional position, in which the rear window is essentially shaded. In the functional position, the pull rod assembly is located at the top end of the two guide rails.
The known roller blind is activated with the aid of linear push elements which are guided in the guide rails safe from buckling and which are driven by means of an electric motor. The wind-up shaft is biased with a spring motor in order to maintain a constant tensile stress in the roller blind in a wind-up direction.
Due to the curvature of the roof and, correspondingly, the curved upper edge of the rear window, when the roller blind is extended, there is still a light gap between the pull rod assembly and the upper edge of the rear window. The gap is unavoidable in the known arrangement due to the straight profile in the pull rod assembly. On the other hand, a straight profile on the pull rod assembly is desirable because this creates the most favorable installation and wind-up relationships.